STOP leg clots-Swedish multicentre trial of outpatient prevention of leg clots: study protocol for a randomised controlled trial on the efficacy of intermittent pneumatic compression on venous thromboembolism in lower leg immobilised patients

INTRODUCTION

Leg immobilisation in a cast or an orthosis after lower limb injuries is associated with a high risk of complications of venous thromboembolism (VTE) and hampered healing. Current pharmacoprophylaxes of VTE are inefficient and associated with adverse events. Intermittent pneumatic compression (IPC) could represent a novel, efficient and safe VTE-prophylactic alternative that may enhance injury healing. The aim of STOP leg clots is to assess the efficacy of adjuvant IPC-therapy on reduction of VTE incidence and improvement of healing in lower leg immobilised outpatients.

METHODS AND ANALYSIS

STOP leg clots is a multicentre randomised controlled superiority trial. Eligible patients (700 patients/arm) with either an acute ankle fracture or Achilles tendon rupture will be randomised to either addition of IPC during lower-leg immobilisation or to treatment-as-usual. The primary outcome will be the total VTE incidence, that is, symptomatic and asymptomatic deep venous thrombosis (DVT) or symptomatic pulmonary embolism (PE), during the leg immobilisation period, approximately 6-8 weeks. DVT incidence will be assessed by screening whole leg compression duplex ultrasound at removal of leg immobilisation and/or clinically diagnosed within the time of immobilisation. Symptomatic PE will be verified by CT.Secondary outcomes will include patient-reported outcome using validated questionnaires, healing evaluated by measurements of tendon callus production and changes in VTE-prophylactic mechanisms assessed by blood flow and fibrinolysis. Data analyses will be blinded and based on the intention-to-treat.

ETHICS AND DISSEMINATION

Ethical approval was obtained by the ethical review board in Stockholm, Sweden, Dnr 2016/1573-31. The study will be conducted in accordance with the Helsinki declaration. The results of the study will be disseminated in peer-reviewed international journals.

TRIAL REGISTRATION

NCT03259204.

TIME SCHEDULE

1 September 2018 to 31 December 2022.

Reverse shoulder arthroplasty has a higher risk of revision due to infection than anatomical shoulder arthroplasty

Aims

The aim of this study was to use national registry database information to estimate cumulative rates and relative risk of revision due to infection after reverse shoulder arthroplasty.

Patients and Methods

We included 17 730 primary shoulder arthroplasties recorded between 2004 and 2013 in The Nordic Arthroplasty Register Association (NARA) data set. With the Kaplan–Meier method, we illustrated the ten-year cumulative rates of revision due to infection and with the Cox regression model, we reported the hazard ratios as a measure of the relative risk of revision due to infection.

Results

In all, 188 revisions were reported due to infection during a mean follow-up of three years and nine months. The ten-year cumulative rate of revision due to infection was 1.4% overall, but 3.1% for reverse shoulder arthroplasties and 8.0% for reverse shoulder arthroplasties in men. Reverse shoulder arthroplasties were associated with an increased risk of revision due to infection also when adjusted for sex, age, primary diagnosis, and year of surgery (relative risk 2.41 (95% confidence interval 1.26 to 5.59); p = 0.001).

Conclusion

The overall incidence of revision due to infection was low. The increased risk in reverse shoulder arthroplasty must be borne in mind, especially when offering it to men. Cite this article: Bone Joint J 2019;101-B:702–707.

Meta-analysis and suggested guidelines for prevention of venous thromboembolism (VTE) in foot and ankle surgery

PURPOSE

To perform a meta-analysis investigating venous thromboembolism (VTE) following isolated foot and ankle surgery and propose guidelines for VTE prevention in this group of patients.

METHODS

Following a PRISMA compliant search, 372 papers were identified and meta-analysis performed on 22 papers using the Critical Appraisal Skills Programme and Centre for Evidence-Based Medicine level of evidence.

RESULTS

43,381 patients were clinically assessed for VTE and the incidence with and without chemoprophylaxis was 0.6% (95% CI 0.4-0.8%) and 1% (95% CI 0.2-1.7%), respectively. 1666 Patients were assessed radiologically and the incidence of VTE with and without chemoprophylaxis was 12.5% (95% CI 6.8-18.2%) and 10.5% (95% CI 5.0-15.9%), respectively. There was no significant difference in the rates of VTE with or without chemoprophylaxis whether assessed clinically or by radiological criteria. The risk of VTE in those patients with Achilles tendon rupture was greater with a clinical incidence of 7% (95% CI 5.5-8.5%) and radiological incidence of 35.3% (95% CI 26.4-44.3%).

CONCLUSION

Isolated foot and ankle surgery has a lower incidence of clinically apparent VTE when compared to general lower limb procedures, and this rate is not significantly reduced using low molecular weight heparin. The incidence of VTE following Achilles tendon rupture is high whether treated surgically or conservatively. With the exception of those with Achilles tendon rupture, routine use of chemical VTE prophylaxis is not justified in those undergoing isolated foot and ankle surgery, but patient-specific risk factors for VTE should be used to assess patients individually.

LEVEL OF EVIDENCE

II.

Deep Venous Thrombosis and Tendon Healing

Tendon metabolism after acute Achilles tendon rupture (ATR) is associated with major complications related to immobilization, which results in reduced circulation, high risk of deep venous thrombosis (DVT), impaired healing and functional deficits.DVT has been demonstrated to occur in up to 50 % of the patients with ATR. Suffering from a DVT during tendon healing has been demonstrated as an independent predictive factor for impaired patient outcome at 1 year after ATR, suggesting that specific interventions are warranted to prevent DVT. Since pharmacological DVT prophylaxis has low or no effect during lower leg immobilization it is speculated whether adjuvant treatment with intermittent pneumatic compression (IPC) applied during lower limb immobilization can reduce the incidence of DVT.IPC, which acts through mechanical, chemical and molecular mechanisms, has been demonstrated to enhance neuro-vascular ingrowth in a tendon repair model and stimulate collagen production leading to improved maximum force during healing.Recently, a prospective randomized trial compared adjuvant IPC applied under an orthosis versus plaster cast only in ATR patients. The study found at 2 weeks post-operatively 21 % DVTs in the IPC-group compared to 37 % in the control group. Patients that received no IPC treatment exhibited an almost threefold increased odds for DVT, independently of age. Furthermore, using microdialysis technique, adjuvant IPC treatment was shown to increase the metabolic healing activity at 2 weeks post-ATR.Tendon healing is impaired by reduced circulation and DVT. The demonstration that adjuvant IPC effectively reduced DVT incidence, and also is capable of enhancing the metabolic response suggests that IPC treatment may not only be a viable means of prophylaxis against DVT, but possibly also a method of promoting healing.

Intermittent pneumatic compression reduces the risk of deep vein thrombosis during post-operative lower limb immobilisation

Deep vein thrombosis is a common complication of immobilising the lower limb after surgery. We hypothesised that intermittent pneumatic compression (IPC) therapy in outpatients who had undergone surgical repair of acute ruptures of the Achilles tendon could reduce the incidence of this problem.

A total of 150 patients who had undergone surgical repair of the Achilles tendon were randomised to either treatment with IPC for six hours per day (n = 74) under an orthosis or treatment as usual (n = 74) in a plaster cast without IPC. At two weeks post-operatively, the incidence of deep vein thrombosis was assessed using blinded, double-reported compression duplex ultrasound. At this point, IPC was discontinued and all patients were immobilised in an orthosis for a further four weeks. At six weeks post-operatively, a second compression duplex ultrasound scan was performed.

At two weeks, the incidence of deep vein thrombosis was 21% in the treated group and 37% in the control group (p = 0.042). Age over 39 years was found to be a strong risk factor for deep vein thrombosis (odds ratio (OR) = 4.84, 95% confidence interval (CI) 2.14 to 10.96). Treatment with IPC, corrected for age differences between groups, reduced the risk of deep vein thrombosis at the two-week point (OR = 2.60; 95% CI 1.15 to 5.91; p =0.022). At six weeks, the incidence of deep vein thrombosis was 52% in the treated group and 48% in the control group (OR 0.94, 95% CI 0.49 to 1.83). IPC appears to be an effective method of reducing the risk of deep vein thrombosis in the early stages of post-operative immobilisation of outpatients. Further research is necessary to elucidate whether it can confer similar benefits over longer periods of immobilisation and in a more heterogeneous group of patients.

Cite this article: Bone Joint J 2015;97-B:675–80.

Can foot compression under a plaster cast prevent deep-vein thrombosis during lower limb immobilisation?

We hypothesised that adjuvant intermittent pneumatic compression (IPC) beneath a plaster cast would reduce the risk of deep-vein thrombosis (DVT) during post-operative immobilisation of the lower limb. Of 87 patients with acute tendo Achillis (TA) rupture, 26 were prospectively randomised post-operatively after open TA repair. The treatment group (n = 14) received two weeks of IPC of the foot for at least six hours daily under a plaster cast. The control group (n = 12) had no additional treatment. At two weeks post-operatively all patients received an orthosis until follow-up at six weeks. At two and six weeks the incidence of DVT was assessed using colour duplex sonography by two ultrasonographers blinded to the treatment. Two patients withdrew from the study due to inability to tolerate IPC treatment. An interim analysis demonstrated a high incidence of DVT in both the IPC group (9 of 12, 75%) and the controls (6 of 12, 50%) (p = 0.18). No significant differences in incidence were detected at two (p = 0.33) or six weeks (p = 0.08) post-operatively. Malfunction of the IPC leading to a second plaster cast was found to correlate with an increased DVT risk at two weeks (ϕ = 0.71; p = 0.019), leading to a premature abandonment of the study. We cannot recommend adjuvant treatment with foot IPC under a plaster cast for outpatient DVT prevention during post-operative immobilisation, owing to a high incidence of DVT related to malfunctioning of this type of IPC application.